1. Field of the Invention
The present invention is in the field of portable electronic equipment, and, in particular, is in the field of portable computers having hinged enclosures wherein, when the covers of the hinged enclosures are closed, a switch is activated to enable the portable computer to enter a suspended mode of operation to reduce the power consumption of the portable computer.
2. Description of the Related Art
Portable electronic equipment, such as portable computers (e.g., laptop computers, notebook computers, palm computers, and the like), are powered by batteries when operated away from a convenient AC power source. Because the operating capacities of batteries are limited, much effort has been expended in reducing the power required by the portable computers. In particular, such portable computers typically include a microprocessor, one or more disk drives, a display, such as a liquid crystal display (LCD), and numerous supporting components, each of which requires power from one or more batteries when the portable computer is operational.
One feature which has been added to certain portable computers is a so-called "suspend switch." Basically, a portable computer has a base portion which supports a keyboard. The base portion is hinged to a cover portion which usually includes the video display (e.g., an LCD). When the cover portion is closed with the portable computer in operation, it is assumed that the because the user is no longer able to observe the display or use the keyboard, it is likely that the user is not going to be actively using the portable computer for awhile, but, on the other hand, the user does not want to turn the portable computer off in order to avoid losing any data that may be resident in the memory of the portable computer. Furthermore, a considerable amount of time is required to gracefully exit some programs and shut the portable computer down, followed by considerably more time to re-boot the computer when the user wants to resume the interrupted task. Thus, instead of requiring the user to shut the portable computer down completely in order to preserve the energy stored in the battery, many portable computers provide a "suspend mode" of operation wherein the power to many energy consuming components, such as the LCD, is turned off, while power continues to be provided to the memory and other selected components necessary to enable the portable computer to successfully resume operation when power is fully restored.
In some portable computers, the suspend mode is activated by a user-activated switch or by a combination of keyboard keys prior to closing the cover. On other portable computers, the suspend mode is automatically activated by a suspend switch which is caused to close (or open) when the cover of the portable computer is closed. This eliminates the need for the user to remember to activate the suspend mode prior to closing the cover of the portable computer.
The automatic suspend switch has proven to be very useful in extending the operating time of a portable computer between battery recharging; however, it has been found that the mechanical operation of the suspend switch does not readily lend itself to economical implementation on portable computers. In particular, in order to facilitate the automation of the manufacturing of portable computers, it is desirable that the suspend switch be mounted directly onto a printed circuit board within the portable computer. However, the bases and covers of many portable computers are constructed from molded plastic parts which tend to have a fairly wide range of dimensional tolerances with respect to the fitting of parts with respect to each other. Thus, it has found to be difficult to find a simple and economical printed circuit board mounted mechanical switch that will consistently operate within the range of tolerances of the plastic parts. In particular, commercially available switches do not have a sufficiently wide range of pre-travel (movement of the switch actuator before the switch contacts engage) and overtravel (permissible movement of the actuator after the switch contacts engage) to accommodate the typical range of positions of the printed circuit with respect to the top of the base of the portable computer. Thus, some portable computers may be constructed with the pre-travel too large such that the switch does not activate when the cover is fully closed, while other portable computers constructed within the same tolerance limits may not have sufficient overtravel such that cover cannot be completely closed or such that the switch or printed circuit board is stressed when the cover is closed.
Thus, it can be seen that a need exists for a printed circuit board mounted switch which can be used in a portable computer or other portable electronic device to accurately detect when a cover or other moveable part is moved to an activating position. In particular, a need exists for such a switch having an accurately determinable pre-travel with respect to the top of the base so that the switch will unfailingly activate when the cover is closed on the base. Further, the switch needs to provide sufficient overtravel so that the cover can completely close without binding and without stressing either the switch, the printed circuit board or the cover. The switch also needs to tolerate a reasonable range of variations in the mounting distance of the printed circuit board with respect to the top of the base.